Spark-plug



A. SCHMIDT.

SPARK PLUG. APPLICATION FILED sEPT.25. ma.

Patented N ov. 16, 1920.

TORN Y.

Flint, Genesee county.

UNITED STATES PATENT OFFICE.

ALBERT SCHMIDT, OF FLINT. MICHIGAN. ASSIGNOR TO CHAMPION IGNITION COM- PANY, 0F FLINT, MICHIGAN, A CORPORATION 0F MICHIGAN.

SPARK-PLUG.

Application filed September 25, 1918.

To all w hom fit may concern Be it known that I, A'Lnizirr Sciniin'r, a citizen of the lnited States. and resident ot Statey ot Michigan, have invented certain new and useful Inr proveinents in Spark-Plugs. ot' which the followingr is a specification.

Vlhe invention relates to spark plugs.

One ot' the ohjects ot' the invention is to devise a spark plug which shall he particularl \v adapted 'for high power. high speed, internal combustion engines such as those used in airplane work. though it will he ohvious that the plug is adaptahle tor use in any inotor.

Another ohject of the invention is to de vise a plug which shall he ot simple and durable construction and inexpensive to nianu facture.

Another ohject of the invention is to devise a plug in which the insulator elements4 will he protected troni fracture.

Another ohject ot' the invention is to de i vise a plug which will eti'ectually withstand intense heat.

Other objects will appear troni the suh- `joined speciiication and clainis.

The drawing shows a vertical sectional view ot the spark plug.

Referring to the drawing. lll is a shell which may he formed with an \v desired torrn ot' exterior such as the lower end ll customarily threaded` and the enlarged upper end 1Q adapted to receive a wrench. The shell l0 on the interior is hored out, forming the insulator chainher lil and the reduced spark ehanil'ier il, the section lo hetween the chanihers i3 and 1l heing heveled as shown. and the upper ridge olt the shell being reduced as at lt tor the purpose ol: turning inwardly to tof-in a clamping flange vtor the parts as hereinz: tter described.

Fitting within the shell lll. and of suh stantiall)7 the saine torni is a porcelain in- .snlator i7 having the enlarged upper portion i8 with the center recess or chainher 19 and the reduced portion Btl with the center hore 2l. Gaskets 9:2 and 233 arel provided about the top and hottoin ot the enlarged portion itl et the insulator and a pressure Specification of Letters Patent.

Patented Nov. 16, 1920.

serial No. 255,575.

ring;r 2l 'formed to lit the upper surface of the insulator and hearing on the upper gasket is provided in order that the reduced flange portion 1G of' the shell may be turned over onto said ringto firmly compress the saine with the enlarged portion ot the insulator and the gaskets to a sealed position within the shell.

A central electrode is suitably secured in the insulator '1T` and has the lower end thereof projecting downwardly to forni the sparking pointy 2t) and the upper end thereotl projecting upwardhv vtroni the inner chainher ,i9 ot the insulator l? and threaded at the extreme upper end. thereot.

ln order to insulate the upper end ot theI electrode a sleeve or tnhe ot mica 2T is placed thereon.

To protect the upper end olf" the niicacovered electrode and also to more securely support the saine, the doine ineinher iti is provided. the lower end ot which lirinly seats on the pressure ring 2 and about the inturned top flange ot' the shell.y said doine nieinher 2S heing formed ot an insulating niaterial and having the top center orifice lil through which the evtrenie upper end of the electrode 25 extends, said electrode having a suitable washer Il() thereon next said donie and a terminal nut 3l threaded or otherwise secured to the extreme top thereotl as eustoinary. i

Emphasis must he inade. on the peculiar arrangement and Ytorni ot the porcelain insulator 17, that is, it is entireliY contained within the shell and has a veryY substantial hody portion irnily clamped therein and provided with proper gaskets and the special pressure ring whereh)v the clamping action necessariY duringassen'ihlj,v will not fracture theiiisulator hut will lirniljv seat the sanie to torni a lining Ifor the entire shell with the lower end thereof projecting downwardliv into the sparking or tire chainn her. and the ei'ilarged portion recessed at 'lSl as descrihed wherehlv the electrorfle sup-V ported by said insulator is przuticalhY oni); in contact therewith tor a` coniparativeli' small part ot the lower length oit the electrode, that is, thepart. ezposed to the hre and heat of the gases of combustion. For this purpose such material as a good grade of porcelain is necessary in order to withstand the intense heat. It is further advantageous to have this part of the insulator comparatively small. or what might be termed a stub section. so that no twisting or torsional stresses will be caused due to any extreme length thereof. and partly for this purpose the recess or chamber 1.() is formed in the insulator though this chambe also permits of the mica sleeve or tube 2T extending down on the electrode whereby short circuiting is prevented between the electrode and the pressure ring 2l.

rThe arrangement olt the electrode as anehored at comparatively the lower end thereof and having the upper end t'ree from the bottom of the insulator chamber 19 permits the upper portion oi the electrode to spring or move slightly with any severe vibration or shock without causing stresses upon the insulator 1T which might fracture or crack the same. and ot' course the electrode Q5 is supported by the dome member :'29 as described whereby the upper end thereof will be held from any excessive movement which might be in any manner transmitted with detrimental eti'ect to the porcelain insulator 1T.

lt will be obvious to those skilled in the art that many modifications and changes may be made without departing trom the spirit and scope ot the invention.

llaving now described my invention what l claim as new and desire to secure by Letters Patent is:

l. spark plug comprising a shell. an insulator supported within said shell. a central electrode supported in said insulator and projecting therebeyond to form a lower sparking point and an upper electrical terminal. and a tube oi' mica extending beyond the upper end of said insulator and covering said upper electrical terminal.

2. A spark plug comprising a shell. an insulator supported within said shell. a central electrode supported in .said insulator and projecting therebeyond to i'orm a lower sparking point and an upper electrical terminal. and a tube of mica covering said upper electrical terminal and extending bevond the upper end of said insulator. and extending also partway into said insulator.

3. A spark plug comprising a shell having an upper insulator chamber and aredueed lower sparking chamber. in insulator having a body portion secured in said insulator chamber and a reduced lower end extending into said sparking chamber and clear ot` the walls thereof. a central electrode anchored in said insulator and having the upper end thereof extending above the upper end ol' said insulator. a mica tube around the upper end of said electrode, and a dome the lower end of which abuts against said shell and which dome incloses said tube and through which the extreme upper end of said electrode extends.

4. A spark plug comprising a shell having an upper insulator chamber and a reduced lower sparking chamber. an insulator having a body portion secured in said insulator chamber and a reduced lower end extending into said sparking chamber and clear of the walls thereof. said insulator being recessed on the upper end about said electrode, a central electrode anchored in said insulator and having the upper end thereof extending above the upper end ol' said insulator. a mica tube around the upper end of said electrode. and extending into the recess in said insulator. and a dome the lower endot which abuts against said `shell and which dome incloses said tube and through which the extreme upper end o'l` said electrode extends.

5. spark plug comprising a shell baving an insulator chamber and a reduced sparking chamber therebelow. an insulator in said insulator chamber and the upper end 'ot which lies below the upper end oi' said lshell. a central electrode supported by said insulator. and a pressure ring litting about the upper edge oil said insulator and pressed thereagainst b v an inwardly turned uppci edge ot' said shell.

(i. A spark plug comprising a shell. a central electrode. an insulator fitting said shell and supporting said electrode and having a beveled upper face. and `the upper end oi' which insulatin' lies below the upper end of said shell. and a pressure ring fitting said insulator on the beveled tace thereot" and clamped therewith in said shell by an inturned upper fiange.

T. A spark plug comprisiiig a shell, a central electrode, a porcelain insulator between the lower part of said electrode and said shell and having a reduced lower end exposed to the gases ot' combustion. and a mica insulator covering the upper part oi' .said electrode and extending beyond the upper end of said insulator.

8. A spark plug comprising a shell. a central electrode` a porcelain insulator between the lower part of said electrode and said shell and having a reduced lower end exposed to the gases of combustion. a mica insulator covering the upper part of said electrode, and a dome of insulating material mclosing said mica tube and the lower end oii `bieb abuts against the upper end of said shell.

S). A spark plug comprising a shell having a center chamber reduced at the lower p. rt thereof. an insulator correspondingly formed and permanently secured in place within said shell, and the upper end of' which insulator terminates below the upper end of said shell, and ported in said insulator.

10. A. spark plug comprising a shell having an internal chamber reduced at ythe lower end thereof, a porcelain insulator fitting within and in contact with the interior of said shell, and having a chamber formed in its upper end, an electrode supported in a central bore provided in said insulator, and a mica tube surrounding said electrode and extending into said chamber in the upper end of said insulator, and which tube extends beyond the upperend of said insulator.

11. A spark plug comprising a shell havin an internal chamber reduced at the lower en thereof, an insulator fitting within and in contact with the interior of said shell, an electrode supported in a central bore provided in said insulator, and a dome capping said Ashell and the againstthe upper end thereof, and through which dome the extreme upper end of said electrode extends.

12. A spark plug comprising an external shell or casing having an insulator chamber within the same, and a spark chamber of reduced diameter located below and communicat-ing with said insulator chamber; an insulator fitting within and permanentlysecured in place in said insulator chamber and having a reduced portion extending into said spark chamber, and the upper end of which insulator terminates below the upper end of said external shell or casing; a central electrode extending through a bore provided in said insulator and terminating below the lower end thereof, and the upper end of which electrode extends above the upper end of said shell or casing; an insulatan electrode sup-- lower end of which abutsv ing tube surrounding the projecting upper end of said electrode; a dome formed of insulating material surrounding said insulating tube and the lower end of which abuts against the upper end of said shell or casing and which dome is provided with a hole Vthrough which the upper end of said eleclerode extends; and a nut in threaded engagement with the upper end of said electrode, and which nut abuts against the upper end of said dome to thereby hold the same in place.

13. In a spark plug, an external shell or casing having an insulator chamber within the same; an insulator located within said insulator chamber and permanently hel in place within the same, and which insulator is provided with a recess in its upper end; a central electrode extending through a bore provided in said insulator and below the lower end thereof, and extending also upwardly through said recess and beyond the upper end of said shell or casing; an insulating tube surrounding the projecting upper end of said electrode and extending downwardly into said recess, yond the upper end of said insulator and beyond the upper end of said shell or casing; a dome formed of insulating material and which dome incloses the free upper end of said insulating tube and the lower end of which abuts against the upper end of said shell or casing, which dome is provided with a centrally located hole through which the upper end of said electrode extends; and a nut in threaded engagement with the upper end ot' said electrode and-which nut abuts against the upper end of said dome to thereby hold the same in place relative to said internal shell or casing.

In testimony whereof I aix my sivnature.

ALBERT SCHMIDT.

and upwardly be- 

